Autoclave



July 14, 193,1. J. J, GREBE 1,814,796

AUTQCLAVE Filed April 23, 1930 INVENTOR ATTORNEY Patented'July 14, 1931 l UNITED STATES EATENT OFFICE g JOI-IN J'. GREBE, OF MIDLAND, MICHIGAN, ASSIG-NOR TO THE DOW CHEMICAL COMPANY, OF MIDLAND, MICHIGAN, A CORPORATION OF MICHIGAN AUTO CLAVE Application filed April 23,

The present invention relates to autoclaves adapted for conducting reactions in liquid media at high temperature and under high pressure when it is desired to includ-e a metal v lic catalyst in the reaction mixture.

If it be attempted toconduct a reaction in a liquid medium which is an electrolyte, and two dissimilar metals are in contact therein, a galvaniccouple is formed and electrochemical action proceeds with the solution of one of the metals and the deposition thereof upon the other metal. If, for instance, it be desired to conduct such a reaction in the presence of copper as catalyst ata temperature and pressure at which copper isv not safe or economically useable as thewall of the pressure ves* sel, then it becomes necessary to use a stronger metal for the vessel and to adopt a construction in which no electrolytic action shall be s-et up which willv either weakenv the pressure vessel byv corrosion thereof .or injure the metallic catalystby deposition of another metal thereon. Such autoclaves have been made of steel or other structural metal suited to the pressure and temperature, lined with the catalyst metal such as copper, such lining being extended through all openings, such as those forvinlet and outlet of material, and into contact with ducts or piping of the same metal whereby it has been intended to prevent any of the liquid being reacted from contacting with two dissimilar metals.

The difficulty m-et with in such construction is to secure a perfect lining and perfect continuity of the lining with the ducts to and from the. autoclave. Should the lining be perforated under pressure or suffer gradual deterioration or should leakage occur in any manner, as at openings closed by flanges or other means, 0r at welds or seams in the metal, the electrolytev would then get into the space between the lining and the pressure shell whereupon corrosion would occur` followed by weakening of the pressurevessel and deterioration of the catalytic activity of the lining.`

I have invented a method of introducing acatalytic metal'into an autoclave or pressure vessel made of a dissimilar metal in which the defects.ofprevious` practice `are 1936.V Serial No; 446,679.

entirely overcome in a very simple, economical manner. I

To the accomplishment of the foregoing and related ends, the invention, then, consists of the means hereinafter fully described and particularly pointed out in the claims, the annexed drawings `and the following description setting forth in detail certain means for carrying out the invention, such disclosed means illustrating, however, some of the various ways in which the principle of the invention may be used.

I construct the autoclave or pressure vessel of al metaly suited to contain the liquid to be reacted, which vessel may be of large or u small diameter, preferably of tubular shape for high-pressure high temperature reactions whereby thicknessand weight of the autoclave is kept at a minimum. I then place a body of the catalytic metal in the autoclave, insulate it therefrom to preventits contact with the wall, using an insulating material substantially unreacted upon by the charge, but without attempting to prevent contact between theliquid reactants andthe pressure vessel wall. A variety of constructions may be employed, preferred and alternative forms of which are illustrated in the drawings.

In said annexed drawings:

Fig. l represents in broken longitudinal cross-sectional View, a cylindrical autoclave of preferred type showing alternative arrangements of parts. Fig. 2 is a longitudinal cross-sectional view of a similar autoclave showing a still further alternative construction.

Referring further to Fig. 1 of the drawings, l is the pressure vessel, which will pref-k erably be cylindrical and of any convenient length, the ends of which may be closed by removable covers as at 2, or may be sealed by welding as at 3. Inlet L'for the liquid to Vbe reacted and outlet 5 are provided, to which suitable ducts may be connected, as indica-ted in dotted lines. Within the pressure vessel is a vtube of the catalyst metal, shown at 6 as a lain tube and at 6 as a corrugated tube. uch tube may be perforated fdesred. The tube 6 or is supported ma out of contact with the pressure vessel by means of insulating plugs or disks 7 and 7', which disks lit loosely within the pressure vessel and are perforated to permit tlow of the reaction mixture into and out of the tube 6. A body or" additional catalyst metal 8 may be illed into tube il, completely or partly filling the same. Such metal may be in the form of sheet-clippings, rings, borings, or the like, having an extended surface exposed to contact wi h the liquid contents of the vessel. Qtherwise the simple, straight, corrugated, or otherwise fabricated tubular construction of the catalytic metal may be more simply employed. It will be seen that the reaction mixture fills the entire pressure vessel l surrounding and iilling the catalyst metal tube butY that the insulating members, 7 and 7, prevent Contact between the metal walll and catalyst metal 6 which are dissimilar andwould, ir contacted, set up electrolytic action.

In Fig. 2 another alternative form of construction'is shown. Here the catalyst metal in aform having an extended surface, represented at 8, is charged into vthe reaction vessel l provided with a lining of insulating material, here shown as in sectional form composed of rings 9 which :are inserted into the reaction Vessel forming therein inner chamber. The ends otA this cha-mberare closed bythe perforated plugs 10 and 10. Here notube or capsule or" the catalyst metal is usedas indicated in Fig. l, but a body of clippings,.borings or the like of the catalyst metal is charged directlyv into the lined reactor, The character of insulation used will depend upon the nature ol the` reactants and the precise'shape, form or manner of application thereof is immaterial. The sectional members 9 may be entire rings or may be made up or" segmentsfas desired. I have found thatl marble, limestone, sintered magnesia, glass, stoneware, silica, or ceramic materials in general, may be used tor insulating lining, the choice depending upon the nature of the liquid react-ant mixture. For lan alkaline liquor a basic material such as marble or sintered magnesia may be selected, while'for an acid liquor aV material such as glass or silica'may be more suitable. F or most purposes a steel reactor pressure vessel may be used, the catalyst metal being chosen required for the process. In some cases metals other than ste-el may be requiredV for the pressureyessel, butits use u fill be in general preferable on account of low cost, strength, and workability.

. To illustrate the advantages of my improvedautoclave, its use 1n the production of al phenol by. reaction between a halogenated aromatic..hydrocarbon and'aqueous alkali will be described, VFor instance, the reaction between chlorobenzene and aqueous caustic soda may be carried out in the presence of copper as catalyst within the temperature range between 300O and 350 C. in about the same length of time and with equally satisfactory results as in a temperature range between 3500 and L00o C. without such catalyst. The lower temperature range is manifestly advantageous because the pressure at the lower temperature is so much less than that at the higher temperature and for other ob vious reasons. I may operate the autoclave of the type herein described intermittently upon batches charged thereinto, or in a continuous manner by flowing a stream of the mixture to be reacted through such autoclave or through an extended tubular system containing an insulated catalyst container dispcsedtherein in like manner. Y

The reactor in this instanceavill preferably be of steel Which .is suitable for the temperature and pressure involved vand upon which the reacting liquid is substantially nonreactive, and marble insulation may be used. lVere, however, Contact between the copper and the walls of the reactor permitted in the presence of the reactants, the steel pressure vessel would be attacked and corroded and iron would tend to be deposited on the copper, entailing a two-fold disadvantage, e. reduction in strength of the pressureV vessel and reduction of catalytic activity or eventually entire elimina-tion ofthe catalytic action of the copper. llVhere, however, the catalyst is disposed as'herein described, no such action can occur and repeated charges oi material may be reacted and withdrawn, or. a con tinuous reactionmay be carried outv over long periods of time, without attention to the catalyst or pressure vessel being required, due to changes therein incident to electrolytic ac- Y tion between dissimilar metals.

There a limited Catalyst metal surface sullicient for the purpose is required, the catalyst may be provided simply in the form of a sheet or shell or tube as in `F ig. l. Where, however, an extended surface is advisable, such may be readily provided by insulating ther inner wall of` the pressure vessel and charging thereinto copper clippings or scrap, as indicated in Fig. 2, or by placing such clippings or scrap in a copper capsule, tube, or casing, as indicated in alternatively in F ig. l. y

It will be seen that I avoid enti rely,A first, the diliculties'of construction involved vin lining a pressure vessel witha ldissimilar metal, and, second, the making and unmaking of connections to such lined vessel while retainingcontinuity of lining to avoid inltroduction of the reacting liquid .into the space between the'lining and the walls of the .pressure vessel. I, further avoid placing the catalytic metal under stresses due to pressure for which purpose-1t is. usually not well =suitedand I am abletov employ steel, iron, or alloys thereof Well suited to hightemperature Y the art that other reactions may and high pressure work in simple forms without accurate tting of catalyst metal thereto.

I have described particularly the reaction for the hydrolysis of halogenated aromatic hydrocarbons by means of aqueous alkalis for production of phenols in the presence of copper but it will be obvious to those versed in be carried out in like manner in the presence of other catalysts than copper as may be required for the speciiic problem in hand. For instance, in reactions involving hydrogenation under pressure, wherein nickel or other metallic catalyst is used, such catalyst may be pro vided advantageously in the manner herein described.

@ther modes of applying the principle of my invention may be employed instead of those explained, change being made as regards the mechanism herein disclosed, provided the means stated by any of the Jfollowing claims or the equivalent of such means be employed.

I therefore particularly point out and distinctly claim as my invention 1. In apparatus of the character described, the combination of a metal pressure vessel, a dissimilar catalyst-metal disposed there in, and electrically insulating means preventing contact between said catalyst-metal and said vessel.

2. In apparatus of the character described, the combination of a steel pressure vessel, a dissimilar catalyst-metal disposed therein, and electrically insulating means preventing contact between said catalyst-metal and said vessel.

3. In apparatus of the character described, the combination of a steel pressure vessel, copper catalyst-metal disposed therein, and

Ielectrically insulating means preventing cony tact between said catalyst-metal andv said vessel.

fl.' In apparatus o the character described, the combination of a tubular metal pressure vessel, a dissimilar catalyst-metal tubular member therein, and electrically insulating means preventing Contact between said catalyst-metal and said vessel.

.5. AIn apparatus of the character described, the combination of a metal pressure vessel,

a dissimilar catalyst-metal having an eX- tended surface disposed therein, and .electrically insulating means preventing contact between said catalyst-metal and said vessel.

6. In apparatus of the character described, the combination of a tubular metal pressure vessel, a dissimilar catalyst-metal tubular member therein, a body of catalyst-metal i having an extended surface within said member, and electrically insulating means preventing contact between said catalyst-metal and said vessel.

7. In apparatus of the character described,

' the combination of a steel pressure vessel,

copper catalyst-metal disposed therein, and electrically insulating means of a basic nature preventing contact between said catalystmetal and said vessel.

8. In apparatus of the character described, the combination of a steel pressure vessel,

copper catalyst-metal disposed therein, and

electrically insulating means of marble pre- Y venting contact between said catalyst-metal and said vessel.

Signed by lme this 13th day of April, 1930.

OI-IN J. GREBE. 

